Rotary joint



July 21, 1959 COQNEY 2,896,173

ROTARY JOINT Filed Oct. 5; 195a HIGH FREQUENCY I l/ SOURCE INVENTOR. IGEORGE R. CooNsY ROTARY .1 GENT George R. Cooney, Lawrence, Mass,assign'or, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application flctober 5, 1953,Serial No. 384,363

3 t'llaims. (Cl. 333-7) The present invention concerns a waveguide jointand selector valve for coupling a stationary rectangular waveguide to aselected one only of a plurality of separate and distinct stationaryrectangular waveguides for passage of electromagnetic energy through thefirst-mentioned rectangular waveguide and the selected one of theplurality of rectangular waveguides.

A further object is to provide a rotary joint for rectangular waveguideswhich separates the rectangular waveguides by a shorter distance thandoes any of the heretofore known devices of this type.

A further object is to provide a rotary joint in combination with aselector valve for rectangular waveguides.

A further object is to provide a rotary joint for rectangular waveguideswherein one of the waveguides that is connected thereto is rotatabletherewith and is coaxial with the axis of rotation of the joint andwherein the joint separates the rectangular waveguides by shorterdistances than does any of the heretofore known devices of this type.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. 1 is the diagrammatic view showing a relationship of this inventionwith associated elements in a radar transmitter and Fig. 2 is anexploded view showing an embodiment of this invention.

There is shown in Fig. 1 a high frequency source 11 connected by arectangular waveguide 13 with a rotary joint 15 that is in turnconnected through a center waveguide 17 to a selector valve 19. Selectorvalve 19 is preferably of the type disclosed in U.S. Patent 2,798,208.Selector valve 19 is connected by rectangular zenith waveguide 25 orrectangular surface waveguide 27 to zenith reflector 29 or surfacereflector 31 respectively. Zenith waveguide 25 and zenith reflector 29together form zenith antenna 33; surface waveguide 27 and surfacereflector 31 together form surface antenna 35.

Rotary joint 15 and selector valve 19 is illustrated in Fig. 2. Rotaryjoint 15 includes a lower rotary joint 41 and an upper rotary joint 43.Lower rotary joint 41 resembles an elbow and transforms high frequencyenergy from rectangular to circular waveguide. This is shown at thebottom of Fig. 2 wherein adaptor 45, which is adapted for connection torectangular waveguide 13' (Fig. 1), is sealed by neoprene gasket 47 toinput flange 49. Thus the elbow that forms lower rotary joint 41transforms the rectangular waveguide of input flange 49 to a circularwaveguide at its outlet end 51. An example of a waveguide structure fortransforming rectangular to circular waveguide is shown in U.S. Patent2,584,399. Fixedly mounted in sealed relation on top of lower rotaryjoint 41 is a lower housing 53 that is sealed from lower rotary joint 41by oil seal 55 and adjusted into proper clearance by laminated shim 57.Bolts 59 fasten lower Patent "ice housing 53 to lower rotary joint 41.Secured on top of lower housing 53 by means of screws 61 is an upperhousing 63. Lower rotary joint 41, lower housing 53 and upper housing 63form a fixed unit of the radar transmitter.

Inside the space defined by lower housing 53 and upper housing 63 is arotatable waveguide element 65 that at its lower end is supported forrotation in a lower roller bearing 67 seating in lower housing 53 andshielded by shield 69 and that at its upper end is supported forrotation in an upper roller bearing 71 seating in upper housing 63 andsealed by a felt oil seal 73. Upper roller bearing 71 is retainedagainst axial displacement upward in upper housing 63 by means ofretainer ring 75 that is fitted against upper housing 63 by laminatedshim 77 and secured in place by screws 79.

Waveguide element 65 comprises a lower inlet stub 81 that has a circularwaveguide (not shown) adapted for communication with the circularwaveguide outlet 51 of lower rotary joint 41. The upper extremity ofwaveguide element 65 forms an upper outlet stub 83 having a rectangularwaveguide 85 that is adapted for communication with rectangular centerwaveguide 17 (Fig. 1). Lower inlet stub 81 is adapted to seat forrotation in lower roller bearing 67 and upper outlet stub 83 is adaptedto seat for rotation in upper roller bearing 71. Between lower inletstub 81 and upper outlet stub 83 is disposed a U-shaped waveguideelement 87 that is rectangular in cross-section. The U-shaped element isstrengthened by a brace 88. The purpose of the U-shaped waveguideelement 87 is to get the rectangular waveguide 17 in line with the axisof rotation of the joint for easy connection to the selector valve 19;the construction of waveguide element 87 is shown in detail in Fig. 2.

Both the lower rotary joint 41 and the upper rotary joint 43 containirises and transformers for proper int-- pedance matching and theassembly is designed to minimize the standing-wave ratio and to providesufiicient clearance so as not to arc with a line voltage about 10%above nominal to the modulator associated with the high frequency source11.

Upper outlet stub 83 of the impedance matcher 65 is mechanically coupledwith the lower extremity of center waveguide 17 (Fig. 1). The upperextremity of center waveguide 17 is mechanically coupled to the lowerextremity of selector valve 19. Selector valve 19, center waveguide 17and upper rotary joint 15 rotate together in train.

In operation, assuming that selector valve 19 as seen in Fig. 1 is inposition to feed high frequency energy through zenith waveguide 25 tozenith reflector 29 and assuming that it is desired to operate the radartransmitter on surface search, selector valve 19 is moved from thesolid-line position to the dotted-line position in Fig. l to feed highfrequency energy through surface waveguide 27 to surface reflector 31.Conversely, selector valve 19 may be moved from the dotted line positionto the solid line position in Fig. 1. Rotation of selector valve 19causes center waveguide 17 and rotary joint 15 that is mechanicallycoupled'thereto to rotate together through the angular displacement ofselector valve 19.

At all times during operation high frequency energy fed into rotaryjoint 15 (Fig. 1) through input flange 49 (Fig. 2) is transformed inlower rotary joint 41 to circular waveguide at outlet 51. Energy is fedfrom outlet 51 through the circular waveguide of lower inlet stub 81 ofwaveguide element 65 where the energy is transformed to rectangularwaveguide. The energy is fed outwardly through rectangular waveguide 85to waveguide element 65 to zenith antenna 33 or surface antenna 35.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwith than as specifically described.

I claim:

1. In combination, a selector valve including a rectangular waveguideportion rotatable to any one of a plurality of angularly spacedoperative positions for communication with any one of a correspondingplurality of antennas; a rotary joint including support means, awaveguide member secured to said support means, said member being formedwith a rectangular waveguide termination at one end, a circularwaveguide termination at its opposite end and a transition portiontherebetween, a generally U-shaped rectangular waveguide member, a bracesecured between the ends of said U-shaped member, means secured to theoutside end of one of the legs of said U-shaped member to provide acircular waveguide termination to said U-shaped member; the other leg ofsaid U-shaped member being arcuately bent substantially ninety degreesto terminate coaxial with the circular waveguide termination on the oneleg of said U-shaped member, said U-shaped member and saidlast-mentioned means secured thereto being mounted for rotation on saidsupport means with the circular waveguide terminations of saidlast-mentioned means and said first-mentioned waveguide member inregistration; and a length of straight rectangular waveguide connectedbetween the rectangular waveguide portion of said selector valve and thetermination of the ninety degree bend of said .U- shaped member.

2. A waveguide joint for coupling a stationary rectangular waveguide toa selected one of a plurality of separate and distinct stationaryrectangular waveguides for passage of electromagnetic energy throughsaid firstmentioned rectangular waveguide and the selected one of saidplurality of rectangular waveguides, comprising: a waveguide memberhaving a rectangular waveguide termination at one end for connection tosaid first-mentioned rectangular waveguide and having a circularwaveguide termination at its other end, a rectangular waveguide memberhaving a circular waveguide termination adjacent one end thereof inregistration with the circular Waveguide termination of said firstwaveguide member and supported for rotation about the axis of thecircular waveguide termination thereof, said rectangular waveguidemember being shaped along the length thereof so that its other end istransverse to the axis of rotation whereby said other end ispositionable along a circular path, a plurality of rectangular waveguideterminations for connection to said plurality of separate and distinctstationary rectangular waveguides, respectively, and mounted in arcuatespaced relation along said path whereby said waveguide joint may beselectively positioned to establish a passage for electromagnetic energyfrom the rectangular waveguide termination of said first waveguidemember and the selected one only of said plurality of rectangularWaveguide terminations in said circular path.

3. A waveguide joint as defined in claim 2 wherein said rectangularwaveguide member having said circular waveguide termination adjacent oneend thereof is generally U-shaped for a portion of its length extendingfrom its circular waveguide termination and for a succeeding portion ofits length is coaxial with its circular waveguide termination andterminates in a portion that is transverse to the portion coaxial withthe circular waveguide termination.

References Cited in the file of this patent UNITED STATES PATENTS2,531,455 Barrow et a1. Nov. 28, 1950 2,556,869 Charles June 12, 19512,584,399 Preston Feb. 5, 1952 2,596,398 Habich May 13, 1952 2,654,868Zaleski Oct. 6, 1953 FOREIGN PATENTS 667,290 Great Britain Feb. 27, 1952

